// Copyright 2015-2018 Parity Technologies (UK) Ltd.
// This file is part of Parity.

// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Parity.  If not, see <http://www.gnu.org/licenses/>.

// Copyright 2019 Conflux Foundation. All rights reserved.
// Conflux is free software and distributed under GNU General Public License.
// See http://www.gnu.org/licenses/

//! Serializable wrapper around vector of bytes

use rustc_hex::{FromHex, ToHex};
use serde::{
    de::{Error, Visitor},
    Deserialize, Deserializer, Serialize, Serializer,
};
use std::fmt;

/// Wrapper structure around vector of bytes.
#[derive(Debug, PartialEq, Eq, Default, Hash, Clone)]
#[allow(dead_code)]
pub struct Bytes(pub Vec<u8>);

impl Bytes {
    /// Simple constructor.
    pub fn new(bytes: Vec<u8>) -> Bytes { Bytes(bytes) }

    /// Convert back to vector
    #[allow(dead_code)]
    pub fn into_vec(self) -> Vec<u8> { self.0 }
}

impl From<Vec<u8>> for Bytes {
    fn from(bytes: Vec<u8>) -> Bytes { Bytes(bytes) }
}

impl Into<Vec<u8>> for Bytes {
    fn into(self) -> Vec<u8> { self.0 }
}

impl Serialize for Bytes {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where S: Serializer {
        let mut serialized = "0x".to_owned();
        serialized.push_str(self.0.to_hex::<String>().as_ref());
        serializer.serialize_str(serialized.as_ref())
    }
}

impl<'a> Deserialize<'a> for Bytes {
    fn deserialize<D>(deserializer: D) -> Result<Bytes, D::Error>
    where D: Deserializer<'a> {
        deserializer.deserialize_any(BytesVisitor)
    }
}

struct BytesVisitor;

impl<'a> Visitor<'a> for BytesVisitor {
    type Value = Bytes;

    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        write!(formatter, "a 0x-prefixed, hex-encoded vector of bytes")
    }

    fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
    where E: Error {
        if value.len() >= 2 && &value[0..2] == "0x" && value.len() & 1 == 0 {
            Ok(Bytes::new(FromHex::from_hex(&value[2..]).map_err(|e| {
                Error::custom(format!("Invalid hex: {}", e))
            })?))
        } else {
            Err(Error::custom("Invalid bytes format. Expected a 0x-prefixed hex string with even length"))
        }
    }

    fn visit_string<E>(self, value: String) -> Result<Self::Value, E>
    where E: Error {
        self.visit_str(value.as_ref())
    }
}

#[cfg(test)]
mod tests {
    use rustc_hex::FromHex;
    use serde_json;

    use super::*;

    #[test]
    fn test_bytes_serialize() {
        let bytes = Bytes("0123456789abcdef".from_hex().unwrap());
        let serialized = serde_json::to_string(&bytes).unwrap();
        assert_eq!(serialized, r#""0x0123456789abcdef""#);
    }

    #[test]
    fn test_bytes_deserialize() {
        let bytes1: Result<Bytes, serde_json::Error> =
            serde_json::from_str(r#""""#);
        let bytes2: Result<Bytes, serde_json::Error> =
            serde_json::from_str(r#""0x123""#);
        let bytes3: Result<Bytes, serde_json::Error> =
            serde_json::from_str(r#""0xgg""#);

        let bytes4: Bytes = serde_json::from_str(r#""0x""#).unwrap();
        let bytes5: Bytes = serde_json::from_str(r#""0x12""#).unwrap();
        let bytes6: Bytes = serde_json::from_str(r#""0x0123""#).unwrap();

        assert!(bytes1.is_err());
        assert!(bytes2.is_err());
        assert!(bytes3.is_err());
        assert_eq!(bytes4, Bytes(vec![]));
        assert_eq!(bytes5, Bytes(vec![0x12]));
        assert_eq!(bytes6, Bytes(vec![0x1, 0x23]));
    }
}
